gh-107619: Extend functools LRU cache docs with generators and async functions (#107934)

Co-authored-by: Adam Turner <9087854+AA-Turner@users.noreply.github.com>
Co-authored-by: Kumar Aditya <kumaraditya@python.org>

Author: 3 people

Doc/library/functools.rst

@@ -226,8 +226,9 @@ The :mod:`functools` module defines the following functions:
 
    In general, the LRU cache should only be used when you want to reuse
    previously computed values.  Accordingly, it doesn't make sense to cache
-   functions with side-effects, functions that need to create distinct mutable
-   objects on each call, or impure functions such as time() or random().
+   functions with side-effects, functions that need to create
+   distinct mutable objects on each call (such as generators and async functions),
+   or impure functions such as time() or random().
 
    Example of an LRU cache for static web content::